Thursday, May 13, 2010

Chipping off the Old Block

Today I'll make a mate for the neck. The top block is a piece of alder, which is a relatively soft timber. It's easy to carve but has more "substance" than basswood. Poplar is another traditional choice, but it's stringy and not pleasant to cut with carving tools. I've marked the face of the block previously - here, I'm marking the face which will eventually be glued to the soundboard.

I'll saw off the excess material. You can see a screw hole that goes through the block. It will help secure the block to the mold. Later, it will house a screw that will aid in affixing the neck to the block.

More sawing, to angle the top of the block. I like these Japanese dozuki saws. They glide like butter.

There now. Much better. A couple of licks with the block plane left this interesting faceted form.

Here's the 2" wood screw that pulls the block to the mold. The protruding plywood landing houses two more short screws that pull the block down to line up with the plane of the mold.

Out comes the flat-bottomed spoke shave to bring the block into round.

A pattern-maker's rasp further refines the shape. I'm aiming for a smooth flowing curve that continues the shape of the bowl down to the neck profile tracing. Some masking tape protects the waxed surface of the mold somewhat from dings and scuffs. I'll use a broad chisel to perfect the transition from mold to block, and then file to smooth out the rough surface left by the rasp.

Here's a flexible drafting curve to mark out the shape of the facets. These aren't really set in stone - I'll sometimes file the surface to refine the shape when fitting ribs.

A smooth file makes a very slight concavity. This aids in achieving a tight joint between each rib.